The invention relates to a bolt capable of fastening two members, which involve dimensional dispersion in a spacing therebetween and positions of centers of holes intended for fastening, while absorbing such dispersion, a method of fastening members with the use of the bolt, and a method of releasing fastening.
In the case where both ends of a lengthy member called an inner panel reinforcement 52 (hereinafter referred to as xe2x80x9creinforcementxe2x80x9d) is mounted on an end surface of a car body 51 as shown in, for example, FIG. 13, the car body 51 and the reinforcement 52 are susceptible of dispersion in positions where bolts are mounted, due to dispersion in press work and assembly accuracy of the car body 51 and the reinforcement 52. Conventionally, bolting to the car body 51 is performed by making an adjusting member 53 intervene, which is L-shaped in cross section, on one side of the reinforcement 52, and making use of a slot 54 of the adjusting member 53 to adjust relative positions of the adjusting member 53 and the reinforcement 52. However, when such adjusting member 53 is used, there is caused a problem that the number of parts increases as compared with the case where the reinforcement 52 is bolted directly, and the number of bolts being fastened also increases, which leads to an increase in manday for the fastening work.
The invention has been thought of to solve the above-mentioned problems of the prior art and to provide a bolt capable of surely and readily bolting two members, separated by a space and having dispersion in dimensional accuracy, without the use of any adjusting member and while absorbing the dispersion, a method of fastening members with the use of the bolt, and a method of releasing fastening.
To solve the above-mentioned problems, a bolt according to the invention is one for integrally fastening a first member and a second member, which are spaced away to each other, the bolt comprising a cylindrical-shaped collar bolt provided on a portion of an outer peripheral surface thereof with an external thread portion and on an inner peripheral surface thereof with an internal thread portion, and a bolt body having in an area of one end of a shank an external thread portion capable of threading into the internal thread portion of the collar bolt and a head on the other end thereof, and wherein either of the external thread portion of the bolt body and the internal thread portion of the collar bolt is formed with a special thread ridge portion, which requires torque more than that required for engagement of normal thread ridges when engagement of the external thread portion of the bolt body and the internal thread portion of the collar bolt is to be released.
Meanwhile, a method of fastening two spaced members with the use of a bolt according to the invention comprises imparting torque to the bolt to cause the external thread portion of the collar bolt to be threaded into an internal thread portion formed in a threaded hole of one of the members (first member) being fastened, after a lower end of the collar bolt is caused to abut against a surface of the other of the members (second member), further imparting torque to the bolt to release threading of the external thread portion of the bolt body and the internal thread portion of the collar bolt to separate the collar bolt from the bolt body, and thereafter threading the external thread portion of the bolt body into a internal thread portion formed in a threaded hole of the second member to integrally fasten the two spaced members.
Also, a method of releasing fastening of two spaced members, that is a first member and a second member, which have been fastened together according to the above-mentioned method, comprises, by reversely rotating the bolt body of the bolt, performing in order the steps of releasing threading of the external thread portion of the bolt body and the internal thread portion of the second member, again performing threading of the external thread portion of the bolt body and the internal thread portion of the collar bolt, and releasing threading of the external thread portion of the bolt body and the internal thread portion of the first member.